This invention relates generally to Graphical User Interfaces (GUIs) and, more particularly, to GUIs useful in connection with positioning, orienting and operating a multiple electrode catheter within a patient's body for diagnostic, therapeutic or other purposes.
Multiple electrode catheters, such as those shown and described in U.S. Pat. Nos. 5,595,183 and 5,487,391 commonly owned by the assignee hereof, are useful in a variety of medical diagnostic and therapeutic procedures. Such catheters are particularly useful in diagnosing and treating certain cardiac disorders, such as arrhythmias, that can occur for example when localized areas of abnormal tissue within the heart disrupt the normal sinus rhythm.
Today, physicians examine the propagation of electrical impulses in heart tissue to locate aberrant conductive pathways. The techniques used to analyze these pathways, commonly called "mapping," identify regions in the heart tissue, called foci, which can be ablated to treat the arrhythmia.
One form of conventional cardiac tissue mapping techniques uses multiple electrodes positioned in contact with epicardial heart tissue to obtain multiple electrograms. The physician stimulates myocardial tissue by introducing pacing signals and visually observes the morphologies of the electrograms recorded during pacing. The physician visually compares the patterns of paced electrograms to those previously recorded during an arrhythmia episode to locate tissue regions appropriate for ablation. These conventional mapping techniques require invasive open heart surgical techniques to position the electrodes on the epicardial surface of the heart.
Another form of conventional cardiac tissue mapping technique, called pace mapping, uses a roving electrode in a heart chamber for pacing the heart at various endocardial locations. In searching for the VT foci, the physician must visually compare all paced electrocardiograms (recorded by twelve lead body surface electrocardiograms (ECG's)) to those previously recorded during an induced VT. The physician must constantly relocate the roving electrode to a new location to systematically map the endocardium.
These techniques are complicated and time consuming. They require repeated manipulation and movement of the pacing electrodes. At the same time, they require the physician to visually assimilate and interpret the electrocardiograms.
Multiple electrode catheters are effective in simplifying cardiac mapping and ablation procedures. Such catheters make it possible to simultaneously obtain data from several locations within the heart or other organ using a single catheter. During such procedures, the multiple electrode catheter is introduced into a chamber of the heart using known, minimally invasive techniques. The catheter's progress through the vein and into the heart can be followed on a fluoroscope. Radiopaque markers on the catheter enhance the fluoroscopic visibility of the catheter. Once proper deployment within the heart is verified by the fluoroscopic image, localized electrical activity within the heart is monitored by means of the individual electrodes. By noting particular types and patterns of abnormality in the sensed waveforms, the physician is able to identify areas of abnormality in the heart tissue. The abnormal tissues can then be ablated or otherwise treated to remedy the condition.
Various advances in the catheter art now make it possible to include a multitude of individual electrodes (e.g., sixty-four individual electrodes) in a single diagnostic or mapping electrode. It is reasonable to believe that further advances will enable still more electrodes to be used. However, as more and more electrodes are added, it becomes more and more difficult for the attending medical personnel to visualize and interpret the additional data that are made available by such devices. Maximum device effectiveness is realized when the attending medical personnel are able quickly and accurately to visualize the catheter within the body and interpret the information the device is providing. Along with the greater resolution made possible by multiple electrode catheters comes the need for simplified systems and methods of data interpretation.
In one prior data interpretation approach, the various waveforms acquired by the individual electrodes are displayed on a screen. The medical personnel need to mentally integrate the heart activity and position data as displayed on the recorder and fluoroscopy screens in order to assess the health of the underlying tissue. This approach requires a considerable degree of skill and experience on the part of the attending medical personnel. Furthermore, information regarding the relative location of an ablation catheter with respect to the multiple electrodes is not readily available. More significantly, the system becomes impractical and unwieldy as the number of electrodes increases.
In another prior approach, information acquired from a number of sequential locations of a roving electrode is digitally sampled and combined to construct a model "surface" that is displayed on a screen and that visually represents the tissue under consideration. Although much easier to interpret than the prior approach that required mental integration of various inputs, this system, too, provides an unrealistic representation that requires skill and experience to use effectively. Furthermore, the surface is difficult to generate as it requires that a roving electrode be moved over the surface of the heart to reconstruct its geometry point by point. To get reasonable accuracy, a high, sometimes impractical, number of points is necessary.
As the number of electrodes, and, hence, the volume of raw data, increase, it becomes more and more important to display data in a form that can be readily interpreted and understood by the attending medical personnel. Furthermore, it might be desirable to display information in such a way that it can be easily related by the physician to information provided by existing visualization or imaging systems, such as a fluoroscopic system. Visually based systems, which enable such personnel to "see" what is happening, offer a viable means of presenting large amounts of data in a form that can be readily grasped and understood. Graphical user interfaces are one means by which such a goal can be achieved.